Cytopenia - NOT Fanconi anaemia

Gene: ACKR1

Green List (high evidence)

Comment on list classification: The ACKR1-related Duffy-null phenotype (or ACKR1/DARC-associated neutropenia, ADAN) is fairly common, particularly in Black individuals. However, as reviewed by Carl Fratter, diagnosis of ADAN would explain the mildly reduced neutrophil counts and help guide further clinical management of patients.

Created: 17 Jun 2026, 1:58 p.m. | Last Modified: 17 Jun 2026, 1:58 p.m.

Panel Version: 5.6

PMID: 35994632 Merz et al., 2023
The study found that 66.7% (80 of 120) of Black individuals had the Duffy-null phenotype and that there is a significant difference in absolute neutrophil counts (ANCs) between Duffy-null and Duffy non-null individuals (P < 0.001). Additionally, 19 of 80 (23.8%) Duffy-null individuals had an ANC of <2000 cells per μL compared with no Duffy non-null individuals. The Duffy-null phenotype is clinically insignificant; however, authors postulate Duffy-null-specific ANC reference ranges should be developed, and the term 'benign ethnic neutropenia' should be replaced with 'Duffy-null associated neutrophil count'.

https://www.hematology.org/education/danc - Duffy-null individuals have no increased risk of infection but are often incorrectly labeled as having neutropenia - reason for inclusion of this gene

ACKR1 is associated with AD, AR [Blood group, Duffy system], OMIM:110700 in OMIM (accessed 17th Jun 2026).
Duffy null is characterized by the presence of Fy(b) antibodies on nonerythroid cells, but an absence of Fy(b) on erythrocytes.

Created: 17 Jun 2026, 1:47 p.m. | Last Modified: 17 Jun 2026, 2:01 p.m.

Panel Version: 5.6

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
[Blood group, Duffy system], OMIM:110700

Publications

• 35994632

Green List (high evidence)

ACKR1/DARC-associated neutropenia (ADAN) is characterised by low blood neutrophil counts without increased infection risk. The condition is also known as benign ethnic neutropenia (BEN) and Duffy-null associated neutrophil count (DANC).
Many patients referred for the R91 panel have a mildly reduced neutrophil count; therefore, it is helpful to include this gene in the panel as, in the absence of other identified causes, diagnosis of ADAN explains the mildly reduced neutrophil count. In addition, this can help direct further reflex testing (e.g. if only ADAN diagnosed on R91 and patient also has anaemia, then R92 may be appropriate).
There are many publications; above, we have included European guidelines which include recommending testing for ADAN where appropriate.
This review is from CSGLH lab team providing specialist haematology and has been supported by requests from specialist clinicians.

Created: 11 Jun 2026, 2:55 p.m. | Last Modified: 11 Jun 2026, 2:55 p.m.

Panel Version: 5.2

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
OMIM 611862 ACKR1/DARC-associated neutropenia (ADAN)

Publications

• PMID: 37008163

Variants in this GENE are reported as part of current diagnostic practice

I don't know

Initial gene list (Consensus Genes for Haem Panels 17.12.18_KCH.xlsx) collated by Frances Smith Viapath Kings College Hospital February 2019 on behalf of London South GLH for the GMS Haematology specialist test group. Gene Symbol submitted: ACKR1; Suggested intial gene rating: I don't know; Are variants in this gene part of your current diagnostic practice? Yes; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal; Phenotypes: 613665 Benign hereditary neutropenia; PMID(s):

Created: 8 Feb 2019, 1:43 p.m.

I don't know

Gene rating submitted by Frances Smith Viapath Kings College Hospital February 2019 on behalf of London South GLH for the GMS Haematology specialist test group.

Created: 8 Feb 2019, 1:37 p.m.

Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal

Phenotypes
613665 Benign hereditary neutropenia

Variants in this GENE are reported as part of current diagnostic practice